Apparatus for utilizing solar heat.



W. L. R. EMMBT. APPARATUS FOR UTILIZING soLAR HEAT. APPLIUATION FILEDJUNE 1, 1909. 980,505, Patented Jan. 3, 1911.

4 SHEETS-SHEET 2.

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m LR .Emmet In Ventor Will Witnesses:

W. L. R. EMMET. APPARATUS PoR UTILIZING SOLAR HEAT. APPLICATION FILEDJUNE 1l 1909.

980,505, Patented Jan. 3, 1911.

4 SHEETS-SHEET 3.

Inventor: Will'amR-EmmeL f wf-6% b3 AMM/0 7 n@ A i Witnesses:

W. L. R. EMMET. APPARATUS PoR UTILIZING SOLAR HEAT.

APPLICATION FILED JUNE 1, 1909.

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' range of temperature is increase .tady, State of -UNITED STATESA'rerinnr OFFICE.

WILLIAM L. R. EMMET, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERALELECTRIC COMPANY, A CORPORATION 0F NEW YORK.

APPARATUS FOR UTILIZING SOLAR HEAT.

To all 'whom 'it may concern: i

Be it known that I, WILLIAM L. R. EM- Mn'r, a citizen of the UnitedStates, residing in Schenectad in the county of Schenecew York, haveinvented certain new and useful Im rovements in Apparatus for UtilizingSo ar Heat, of which the following is a specification.

The rays of the sun deliver to every part of the earths surface a largeamount of energy, amounting in many cases to more than one watt persquare inch of surface directly exposed. Under ordinary conditionsbodies heated by the sun simply rise toa temperature where cooling, byradiation, conduction and convection, balances the heat received. 'llhusunder ordinary conditions it is impossible to impart any high degree oftemperature because the heat dissipated soon balances that received.

- To convert heat into energy eiiiciently it isv necessary to operatethrough considerable range o tem erature, since the efiiciency of anythermoynamic cycle is virtually proportional to the temperature range.Thus 1f a certain number of heat units can be utilized in makin steam orother useful va or, the. ower o tainable from the steam wil depen uponthe tem erature throu h which it is worked, and wi 1 be lar er as theFrom this it follows that any method of heating liquid or gas for thepurpose of producing power must depend for 1ts etliciency u on thedegree of temperature that can e -ecin its practical em y odiment, oneor morerves- 'sels of suitable shape andv slze which isi-orv 1y areheated externa by the suns rays.

. Water or other fluid or gas is delivered to the vessel under thenecessary pressure, and

Specification of Letters Patent.

by radiation from the vesse Adisturbing any other part.

afterbein-g heated is discharged for application either in the form ofheat or power. The luid thus delivered may be utilized for industrialpurposes in any known way. The vessel is provided with an inclosurewhich freely admits the suns ra s but restrictsas completely as possiblet e dissipation Aof heat from the vessel itself. Statedmore'specifically, the arrangement of the inclosure is such that pathsby which heat or radiation can escape from the vessel heated areintercepted by vacuum chambers or by a single vacuum chamber whichwholly or in part surrounds the vessel. These chambers, owirilig totheir lack of internal atmosphere, cut o the escape of heat byconduction and convection and when internally silvered to render themreflecting also lar ly cutoff losa d. The radiant energy received can-be admitted without passing it through the walls of one of theseyvacuum chambers but it is preferred to admit it through portionsloli-such walls which are made transparent for the purpose.

In carrying out my invention one or a number of vessels are provided,preferably a number, of an suitable sha e and size,

that are sufficient y strong to wlthstand the pressure of the vapor tobe generated. The most convenient way to carr out the in- Y vention isto make a boiler t at comprises a series of tubes placed side-by-sidewith a suitable space between and connect corres onding ends to achambered header so that uid-can flow. into and'A out of the tubesabsorbing heat as it goes. I can advantageously make the tubes andheader of metal, since by so doing they will be relatively light andstrong and occupy only a moderate sized space. One wa to make the boilerwhich possesses many a vantages isto utilize tubes that are closed atone end and at the other are attached to the header. Inside of each tubemay be placed a second and usually concentric tube that does not extendquite to the closed endv of the outer tube so that fluid will flowfrom-one to the other.

` I may also use a barrier of other form orA may dispense with anythinginside of the tube for directing circulation. With these arrangementsthe vacuum-chambered lass jacket or envelop, to.- he referred to ater,can be lreadily removed-or replaced without p The header which connectsthe tubes should be placed at Patented Jan. 3, 1911. v Application ledJune 1, 1909. Serial No.' 499,445.

such a -level or position Ithat it will not shut oit the tubes from thesuns rays. The header may, if` desired, be .arranged to rest on thelectors -or mirrors, suitably placed, to concentrate the radiation onthe tubes andreflec'ting surfaces in the glass envelop to mm1- mizeradiation of heat from the tube surface the.` loss will be relativelyless than with large tubes and no reflectors, and the apparatus as awhole will be more efficient. As it'will be desirableto use a relativelylarge number of small vessels instead ofa lesser number .ofcomparatively large vessels,

the amount of vapor. produced in each will.

be small, and small tubeswill be more desirable than largeon accountn ofcheapness provided the arrangementjjissuch that by aid of reflectorsthey intercept most of the energy which-would otherwise. be lost. Thewater and steam connectionsl leading to and from the tubes can also belmade qulte small 35, of flui although proportioned of course to the towtions the loss b heat will be diminished. Generally speakmg, thediameter, thickness,

Vand length of the tubes will depend upon the pressure at which theboiler is operated, thespace necessary for circulation of low pressuresteam being greater than that required for high pressure steam.

. ATo. reduce the heat losses that would otherwise occur, each vessel isprovided with an inclosure,- some ortion of which at least.

is transparent to reely admit-the rays ofthe sun. The transparentportion'` is 'provided with a vacuum chamber to reduce the radiation,conduction and convection losses of the vessel itself as completely aspossible; The vacuum chamber preferably but not necessarilyincloses orsurrounds the vessel as fully as ossible because the more completely theissipation of heat from the vessel is restricted or'retarded, the hi herwill be the temperature of the vapor w ich will be practicable withoutundue loss. The advantage of this will be apparent when it is rememberedthat the'eiliciency of a thermo-V dynamic cycle is virtually proortional to the temperature ran e as be ore stated.

` Stated more speciica y, each tube or vessel to be heated 1s inclosedin a glassenvelop, the interior of which is evacuated. This envelop ispreferably made with double By reducing the size of the connecwallswhereby the interspace can be sealed v by fusion of glass afterexhaustion so that the vacuum will remain permanent. An-

other way of applying. the same principle is to use suitably shaped,sealed and ex hausted tubes, flattened or circular, as screens tocut offpaths by which heat might escape fro'm the lheated vessel, and to useother heat insulating material to close spaces by which heat mightescape between these tubes.

Since it is diiicult to make an air-tight joint or seal between a metalvessel and an outer glass envelop or jacket and one that will not admitair whene the parts expand and contract unequally, I make the envelop orvessel in the form of a double-walled inclosure with a suitable spacebetween the walls to form a vacuum chamber. I n this manner I avoid theill effects due to unequal expansion and contraction, and furthersimplify the construction since the jackets can beseparately made andthen mounted in place and can be silvered except at the 'part where ra senter. It further has the advantaget at if one jacket is broken it canreadily bereplaced. Owing to the fact that `the. liquid is contained inthe metal vessel or vessels if one of the jackets "is accidentallybroken` or a1r leaks into the chamber' yin the jacket due to adefective. seal or otherwise,

the operation of the apparatus as awhole is not greatly im aired. Thesimplest w-ay to make the enve op or jacket is of two glass tubes onelocated inside of the other andv sealed at the ends. .Where the tubesare long, suplports ma be provided at suitable points t at exten betweenthe tubes and preserve the desired relation of parts. The

outerwall'of the jacket is silvered prefer= ably on the inside for agreater part of its circumference so as to reflect back to the walls ofthe vessel the heat rays which would otherwise be lost. The suns rayswill freely pass through the unsilvered portion which will be located atthe top and be of 'suiicient area to admit all of therays that can acteffectively on the vessel containing liquid to be vaporized. The surfaceof the outer wall should be so shaped that it will act as a concavemirror s o that substantially all the heat radiated from the tube itselfwill be reflected back upon it by the mirrored surface. A'jacket orcovering for the vessel when thus formed is an effective heatinsulatorand will greatly cut oil' the dissipation of energy from the heated wallof the vessel but at the same time will freely admit radiant energy fromthe sun. From this it follows that my improved arrangement has theadvantage that it makes ossible the delivery of energyy toa liqui or gaswith a correspondingly small energy dissipation` cablev to the making ofsteam but also to the heating of air or other gases, water or othervfluids which may be used for producing power or distributing heatenergy.

Since the transparent area in the protecting'envelop through which therays enter must also serve as a path for escape of radiations from theheatedvessel, it is desirable to focus the rayswith external mirrors sothat they can be made to enter a narrow space. vBy this means theadmission of rays is not greatly diminished and the loss by radiationmay be materially cut down, and furthermore the size of the heatedvessel can be reduced in proportion to the area of sunlight interce ted.Preferably each tube would lbe provi ed with two such externa-l mirrorsor reflectors, the reflectors for adjacent tubes being properlydisposed, as for example, back to back. In this way am able toconcentrate or focus more of the suns rays on .each of the tubes thanwould otherwise be possible. 1 j

As a further precaution against losses brought about by corrodedsurfaces, dirt, moisture, etc., the apparatus may be housed in astructure having a glass roof like a greenhouse. Suchl an arrangementwould assist only in confining the heat and may in that way tend toimprove the eliiciency somewhat in spite of the fact that the glasscovering would intercept some of the radiant energy, or glass covers toprotect tubes and reflectors from dirt and rain can be attached to thestructure itself as shown or in some .convenient manner.

lin some cases I may so arrange the apparatus that it .with itsinclosing jackets, mirrors, etc., can be moyed to a position for eachgroup on a hinged' joint which carries both water and steam by which thewhole group with its reflectors can be tipped up and down so that duringthe hours of use the reflectors can be kept in planes where they bestfocus the rays.v This movement can be controlled by clockwork or by adevice actuated by the direction of therays themselves.

lin the accompanying drawings which are illustrative of my invent-ion,Figure 1 is a plan View of my improved boiler; Fig.y 2 Vis a sideelevation of the same; Fig. 3 is a sectional view of one of the tubesand a header connected thereto; Fig. @is a view in side elevation of oneof the jackets or envelops;

,Figa 5is a cross-sectional view of a jacket showing its wallseccentrically arranged; Flg. 61s a View 1n cross-section showingreflectors for focusing. the suns rays on the tubes; Fig. 7 is a detailview showing a jacket with "a .means for compensating for expansion;Fig. 8 is a detail viewshowing a desirable form or construction for ajacket; Fig. 9 shows my improvedboiler supplying steam to a condensingturbine that is directly connected to 'an electric generator; Fi. 10 isa view in cross-section showing a di erent form of my invention; Fig. 11is a cross-section of still another form; Fig. 12 is a detail view of aswivel oint for supporting the header with conduit for conveying fluidto and from the chambers therein; and Fig. 13 is a partial sectionalview 'of a modified form of a vessel or boiler.

Referring to Fig. 1, 10 indicates a metal header to 'which the vesselsor tubes 11 are l header also rforms a support therefor. The

lower end ofthe header is or may be provided with trunions 12 that aresupported in an upright 13 which rests on the ground ortother sultablefoundation. yBy raising or lowering' the upper end of the grid itsinclination with respect to the surface of the earth can be changed tocompensate for changes in the direction of the suns rays. The structureshown, z'. ce., a screw-jack 14. pivoted at thebase, may be taken astypical of any suit-able means for raising and' lowering thel upper endof the grid. The tubes 11 preferably but not necessarily extend bothsides of the header so as to simplify the structure and decrease thenumber of parts and the cost ofmanufacture. The header is provided witha central longitudinal chamber 15, Fig. 3, to which water or other.fluid to be heated is admitted by the pipe 16. To the side walls of thechamber are threaded or otherwise secured metal tubes 17 that are openat both ends. Surrounding each tube is a metal tube 18 t.hatis threadedor otherwisesecred to the outer wall 19 of the header.' The outer end ofthe tube is closed by a screw-threaded plug 2O or other means. With thisarrangement water or lother fluid enters the chamber 15 from the inlet16 and flows through the inner pipe 17 to the end and then turns andHows through the outer tube 18 back into the chamber 21 which is incommunication with the chamber 22. in the header and from which vaporleaves by the outlet 23. Instead of using two tubes, the inner tube canbe omitted and some other means, if desired, employed to direct thecirculation of the fluid. Each of the tubes is provided with a jacket orenvelop 24 some portion of which is made of double-walled, tough,transparent glass, each jacket forming a chamber 25 from v,which the airhas been previously exhausted and a high degree'of vacuum attained.jacket is or may be slipped 'endwise over the.' tubeand on the inner'endrests an asbestos or other washer 26 that forms a cushion to reducebreakage due .to expansion and con-Q..

traction and may also act as a heat insulator; The header is lagged .orotherwise covered with good heat insulating material 27. The

outer end of each jacket engages one orA more asbestos or simllarwashers28. These washers are pressed by a spring 29 against the end of thejacket, -pthe spring acting against an adjustable abutment 30l carriedby a rod 31 threaded into the plug 20 or otherwise supported:Thisarrangement will compensate for expansion and contraction. It

isoto be noted that the conduits admitting fluid to the tubesand'conveying it therefrom are lseparate from 'and independent of thejacket or its walls. The advantage of thisresides in the fact that saidconduits do not have to pass through the vacuum chamber, an' arrangementthat would b e costly in the first place' and uncertain in practicebecause ofair leaks. It also permits of the jackets lbeing assembled andtaken oi the tubes without regard to the connectionstli'ereof.

5 l In Fig;l 4 is shown one of the vacuum jackets or envelops. It/iscomposedof an outer tube 32 and an inner concentric tube V33, thediameter of the latter being slightly; larger than that o f the fluidcontaining tube 18 to` permit of its being readily slipped into place.The. ends of the tubes are connected as 'for example by washer-shaped,pieces 34 which 'are carefully fused to both tubes. The vacuum chamber2 5 may be of any suitable shape and size so long as it inclose orprotect a portion thereof, the restruction by decreasin acts toeffectively reduce the dissipationbf.

heat from .the metal tubes containing the ,iiuid to be heated. As ageneral proposition the vessel" should be jacketedas. completely aspossible.

incloseA the fluid-containing vessel or it may' mainder being protectedby a cheaper form of heat insulating material. The shape and size willof course be governed largely -by the shape and size of the vessel..`Itis of great practical value to so construct the vessel and jacketthat both fca`n be separatelyl made and the latter mountedin placewithout having to disturb any connections or any part of the vessel. Itis also of great' practical value to connect all of the tubes tothe-same header since it simplifies the con- A the'loss'es due. toradiation, and also re uces the number of parts. l

In Fig. 5 is shown an arran ement which possesses certain advantages. nthis re the inner andouter walls 36 and 37 o 4the jacket areeccentrically disposed, the lower portion of the outer wallbein'g'silvered as The portion containing the vacuum chamber may be madeto entirely aeoaoe at 38. The amount of such silvered surface in thisand other lcases will be governed by the area that is required ordesired to admit the suns rays. The silvering will focus the suns rayson the contained vessel or tube, and will also reduce the dissipation ofheat ,from-the tube by reflecting vthe heat back upon the vessel ortube.

` In Fig. 6 is shown an arrangement that possesses certain additionaladvantages. ach tube 4is inclosed in 'a vacuum-cham- `bered .jacket orenvelop and the other wall of the latter is silvered for considerablymore V'of its circumference than those previously describedv to reducethe dissipation of.

heat from the Huid- .fcontaining tube 5 the heavy black line 39indicating such silvering. Extending upwardly from the outer wall ofeachv jacket are two reflectors 40 that embrace a larger .area than theunsilvered portion of the jacket and which are properly sha ed to directthe, suns4 ra s.

through the c ear or unsilvered walls of t e vof some metal such as Monevthat-will take a high polish and will not readily corrode. Thev 'alsohave the advantage of being light as t ey are made of sheet metal, and'at the same time are sufiiciently `strong to maintaintheir proper shapeunder all conditions.

The upper ends of the reflectors are pro-l vided with grooves 42 toreceive and sup'- vport sheets' of glass 43, the latter protecting thereflectors and tubes, from foreign "'material, and also preventing tl1ereflectors from tarnishing.l

In Fig. 7 is s own a form of jacket that is especiall useful. when longtubes are emlT e jacket is composed of a double- `wa ed structure asbefore, and the relation ,of the walls one to thevotherl is maintained'by distance pieces or spacers 45 which may be made of any suitablematerial, such as thin metal for example.: These spacers may be employedwhere` the walls of the jacket are` concentric or otherwise. The numberemployed will depend upon the length of the jacket. The spacers will.reduce the danger of breakage, .and will relieve the inner tube fromstrains to va greater or less degree. The will also revent lthe wallslwhen made t in from co1 apsing ,due to the vacuum in the` chamber. VInthose .cases 1 -where the expansion of, the walls `of the alo may bemade up in relatively short lengths i and mounted on the vessel oneafter the other, as shown. In the latter case disks of yielding material47 will preferably be i1'1- serted between the ends of adjacent sectionsor lengths to reduce the danger of breakage.

. Another Way to make the jackets that is especially useful where theexpansion of the walls is unequal and also to reduce the cost ofmanufacture is shown in Fig. 8. The outer'wall 48 including the righthand end 49'is made in one piece. The inner wall 50 is made in one piecewith the end 51. The

opposite end is provided with an integral flange 52 which is united withthe left hand end of the outer tube. This results in only one joint inthe jacket which is obviously importantv since it reduces the danger ofv.air leaking into the vacuum chamber. Fur- -ther since the walls areonly united at one end they can freely expand and contract withoutdanger of cracking. The use of spacers 45 in this construction is alsodesir-z a le to reduce the danger of breakage and; relieve the joint atthe end of stralns occasioned by its own momentum when the jacket isstruck or moved rapidly.

with the demand. The turbine drives an electric generator or other load57. The turbine exhausts into a ASurface or other condenser 58.Circulating water enters the condenser by the conduit 59 and leaves bythe conduit 60. Vater of condensation is collected in the hot well 61and is conveyed by a pipe 62 to a multistage centrifugal pump 63 forincreasing its pressure. The pump 1s driven by an electric or fluidactuated motor effectively use vapor which is worked at low pressurethrough lsmall ranges of temperatureland volume. The use of such lowpresing apparatus which on account of low pressure and low temperaturewould be1 useless with engines'of the reciprocating type.

In Fig. 10-is shown a further modification of my invention whichpossesses certain advantages in the nature of reduced initial cost. 67indicates a fluid containing vessel or tube. Surrounding it on threesides is a body 68 of heat insulating material such, forexample, asmolded magnesia. This block is made comparatively deep so that thedissipation of heat from the under side of the tube 67 will berestricted. The dissipation of heat from the'sides will also berestricted by said material. The upper 'side of the block is cut away toform a recess 69, and located in this.

the latter being properly shaped to concenvrtrate as fully as possiblethe rays of the sun directly on the vessel. It will be seen in thisligure that the jacket considered as a whole is composed of twoportions, e., the molded block. of insulation68 and the doublet ,walledglass part, member or element 70. In Fig. 9 a boiler having the generalcon- A struction of Figs. 1 and 2 1s provided which supplies steam tothe condensing turbine 55 by the pipe 23. In this pi e is a valve 56that may be taken as typica of any suitable 4 controlling mechanism forthe turbine to vary the admission of steam in accordance:

By locating said member in a recess formed in the block 68 it` can beslipped into place by an endwise movement, or if the reflectors areremoved it can be inserted in place from above; The adjacent blocksabut, and vlo-v cated above the joint between and extending over theside portions of the adjacent members 70 is a layer of felt'75 such asis used for steam pipe covering, or it may be made of asbestos orequivalent material. This material acts as a cushion or pad to reducethe danger of lbreaking the glass and also to revent the circulation ofair through the joint between the blocks and hence reduce heat losses.Situated above the blocks men- -tioned and overlapping the joint betweenis a substantially triangular. shaped piece 76 that assists in unitingthe blocks and also forms a support for the adjacent walls of thereector. vThis piece may be secured in place by bolts v77 that 'extendthrough oritices formed artly in one block and partly in the other. hebolts extend through lates 78 and between the plates and the b ocks, andcovering the joint'between said blocks are pieces 79 to prevent aircirculation and restrict heat dissipation.

In Fig. 11 is shown an arrangement somewhat similar to'that ofFi 10except that two members 70 are emp oyed instead of one. The said membersare made in the sure turbines makes possible the use of boilform of@flattened tubes or not-as is most convenient in practice or the-cheapest or. Y most suitable. The upperl ember is made as before andhas a clear port-ion directly over the vessel to be hea-ted.` Theremainder fof thewalls. is silvered as indicatedby the similar in shapeto the upper and isentirel silvered 4as indicated by the heavy blac 10heavy lblack line 72.- The lower member is line 80. Since the suns raysdo not pass through the bottom member no clear portion is necessary. Onthe contrary, it is desiredone shown in Fig. 10, has certain advantagesin the vway of reducing the escape of heat, and it also occupieslessspace. The upper and lower members are held by blocksV 81 ofy insulatingmaterial having recesses or shoul- `ders to receive and support saidmembers.o

'flhe reflectors 13j-74 are supported as beore.- d f Referringl to Fig..12, I4 have shown a typical means whereby the header vmay be supportedat the bottom, and its angle of inclination changed with respect to thesur- `face of the earth. 85 indicates a projection on the base of theheader 10 containing passages 86 and 87 that communicate with thechambers 15 and 21 respectively. 88 indicates a base thatis aiixed to asuitable suport. It contains conduits 89 and 90, the atter of whichadmits water to the passage 86 and the rformer conveys steam from thepassage-87 andl its connected chambers. The eader andvv its tubes arearranged to swing l about the bolt 91 as an axis. The openings 91athrough the casing kwalls are made segmental so that fluid can freelyflow irrespective of the inclination of the header.

In Fig. 13 is shown a slight modification in the structure of the vesselor boiler. The header 10 is provided with a single chamber 92 thatcontains both the water and the vapor given up thereby. Extending fromthe lheader are tubes or pipes 93 that'are closed at their outer endsand at their inner ends open into said chamber. In thiscase the innertube or baiiier shown in Fig. 3 has been omitted.` The tubes or pipesarel inclosed in jackets or envelops in the manner heretofore described.Water or other fluid is admitted by the pipe 16 and vapor is dischargedby a conduit located at any suitable point. l

It will be seen thatl my invention con! templates either inclosing theHuid containing vessel by means of a vacuum chamber 'as completely aspossible or partially inclosing it by such a chamber, and I aim toembrace such arrangements in my claims'. Whether one arrangement Yor'theother is used, or both m the same apparatus'will be l that the inventioncan be carried out. by other means.

f restricts outward lo'ss of heat from the vesgeverned chiefly by the oerating conditions v and by the cost of manu acture.

' In accordance with the provisions of the patent statutes, I havedescribed the princi le` of" operation of my invention, together w1ththe apparatus which- I now consider tol represent the best embodimentthereof;

'butI desire to have it understood-that the apparatus `shown is onlyillustrative, and

What I claimfas new and desire to .secure by Letters Patent of theUnited States is:

1. In anapparatus o'fthe character described, the combination of a{luid-contain- 'ing vessel that-.is heated externally by a source ofradiant energy, with a jacket therefor which has a transparent ortlonthat freely admits 4energy from sai source and sel and a reectingportion for reflecting h eatradiated from the vessel back upon it.

2. In: an apparatus of the character described, the -combination of afluid-containing vessel that is heated externally by a Vsource ofradiant energy, with a jacket therefor that has a vacuum chamber whichjacket freely admits energy from said source and` restricts outward lossof heat from the vessel. i

3. InV an apparatus of the character described, the combination of aHuid-containing vessel that is heated externally by a source of radiantenergy,oa jacket therefor including adouble-walled structure containinga vacuum chamber, and means for conveyin luid to and from the vessel. .1

4. n an apparatus of the character described, the.. combination of afluid-containing vessel that is heated externally by the lrays of thesun, with a jacket therefor that has a vacuum chamber with a transparentportion throughl which said rays passand act onthe vessel.

5. In an apparatusof the character de- 110 scribed, the combination of a{luid-containing vessel that is'heated externally by the -rays of thesun, with a jacket therefor that r has a vacuum chamber with atransparent portion through which said rays pass and 115 act on theWessel, and a reflecting surface for the jacket to reduce dissipation ofheat from the vessel, the saidreector being located within the vacuumchamber.

`6. In an apparatusl of the`character de- 120 scribed, the combinationof a metal-walled, fluid-containing vessel that is heated externally byla source of radiant energy,with a double walled jacket therefor, whichforms a vacuum chamber, a' portion ofwhich is 125 transparent.

7. In an apparatus of the character described, th'e combination of aHuid-containing vessel that is heated externally by a soure of radiantenergy,` a jacket for the ing vessel that is heated externally by al avacuum chamber, and a reliector which re' iiects the heat radiation-fromsaid vessel back upon it. j

9. In an apparatus of the character described, th combination of Aa{luid-containing vessel that is heated externally by a source of radiantenergy, a doublewalled glass jacket for the vessel that forms a vacuumchamber, and 'a reflecting surface in the vacuuln chamber that surroundsa. portion only of the vessel and reflects heat radiating from saidportion back upon the vessel. 'j

10. ln an apparatus of the character described, the combination of afluid-containsource of radiant energy, and aglass jacket for the vesselthat forms a vacuum chamber, the outer Wall of said jacket beingsilvered on the inside surface except gliene-the radi-ant energy enters.

11. In an apparatus of the ,character described, the combination of afluid-containing vessel that is heated externally by a source of radiantenergy, a jacket for the.

vessel that forms a vacuum chamber and has a transparent port-ion topermit said energy to pass through it, a reflector for directing therays from said source against the vessel, and means for conveying fluidto and from the vessel.

12. lin an apparatus of the character described, the combination of avessel that is heated externally by the ra s of the sun, a jacket forthe vessel that orms a vacuum chamber and has a transparent portion topermit said rays to pass through it, a re hector. for focusing rays ofthe sun on the vessel, and a retlecting surface in the vacu- .um chamberfor reflecting the heat radiating from the vessel back upon it.

13. ln an apparatus of the character 'described, the combination of avessel that is heated externallyby a source of radiant energy, a jackettherefor, which forms a vacuum chamber and hasatransparent por-A tion toadmit said radiant energy, and means separate from and independent ofthe jacket for conveying the fluid to be heated to and from the vessel.i

14h 1n an apparatus of the character described, vthe combination oit vavessel that is heated externally by a source of radiant energy, adouble-Walled glass jacket therefor that forms a chamber from which theair is exhausted, a conduit admitting fluid to the vessel to be heated,and a second conduit for carrying heated fluid from the vessel, the saidconduits bein separate from and independent of the Wa ls of said-jacket.

15. In an apparatus of the character described, the lcombination of ametal-Walled vessel that contains fluid and is heated externally bysolar heat, a double-walled jacket for the vessel which forms a vacuumchamber and has a transparent portion, and a reflector that is madel bysilvering one of the Walls of the jacket.

16. In an apparatus of the character de scribed, the combination of acylindrical ves- `sel that contains fluid and is heated externally bysolar heat, a jackettherefor, comprislng transparent .tubular memberslocated one inside of the other and forming a vacuum chamber, and meansfor conveying fluid to and from the vessel.

17. Inan apparatus of the character described, the combination of aplurality of fluid-containin vessels that extend in the same generalirectionand are heated yexternally by a source of' radiant energy, asupport that is common thereto, and an independent jacket for eachVessel which forms a vacuum chamber, said jackets freely admittingenergy from said source and restrictingv the outward loss of heat Ifromthe vessel.

18. In an apparatus of the character described, the combination of aplurality of fluid-containing tubes that are heated externally by asource of radiant energy, a header that is common thereto, ackets forthe tubes,

each of which formsa vacuum chamber and freely admits energy from saidsource but restricts the outward loss of heat fronrthe tubes, andconduits for conveying iuid 'to and from the header.

19. In an apparatus of the character des'cribed,.the combination of aplurality 'of fluid-containing tubes, a cylindrical jacket for eachtubewhich is slipped over it from one end, the said jacket forming avacuum chamber, a chambered header to which the tubes are connected atone end, and conduits conveying fluid to and from the chambers in theheader.

Q0. lin an apparatus of the characterdescribed, the combination of aplurality of tubes arranged to form a grid, and which are heatedexternallyby a source of solar radiation, jackets for the tubes, eachcomposed of transparent material andV forming a vacuum chamber,reflecting surfaces which reflect the radiation from the tubes back uponthem,

and other reflectors which focus the radiation from the source 'upon thetubes.,

21. ln an apparatus of the character described, the combination of aheader, a plurality of parallel tubes that extend itrom4 one sidethereof and are heated externally by solar radiation, a jacket for eachtube Aabove the tubes for focusing the solar radiation upon them. l

- 22. In an apparatus of the character described, the combination lof avessel that is heated externally by a source of solar radiation, ajacket therefor thatl comprises a double walled structure forming aVacuum f chamber and has a transparent portion, 'a

reflecting surface that incloses a portion only of the vessel andfocuses radiation from said source and also that from the vessel uponsaidves'sel.

23. In an apparatus of lthe character de-l scribed, the combination of avessel that is heated externally by a source of solar radiation,ajackettherefor comprising a double walled glassv structure forming af vacuumchamber, and a yieldin means which'permits the parts'to expan andcontract wlthout breaking the jacket.

24. In an apparatus of the character described, ther combination of ametal tube that lis heated externally by the 'suns rays, a

double-walled tubular glass -jacket therefor which "forms a vacuumchamber and 4is `slip ed: on endwise overthev tube, and a yiel ing meansa-t one end of the jacket `to permit the lass to 'expand and contractwithout brea ing.

25. In an apparatus of the character described, the combination of ametall tube that is heated externally by thesuns rays, a -double-walledtubularg-lass jacket therefor which contains a `vacuum 'chamber and isslipped on vendwise over the tube, a i'xed abutment carried by the tube,anda yielding meansbetween the abutment andone endof the'glass jacket..v Y

, 26. iInan apparatus of the character described, the combination'of avessel, a jacket; therefor comprising glass cylinders located one withinthe other and closed at the ends and containing a -vacuuni chamber, andadevice vto permit of expansion and contraction formedin one ofsaidpcylinders.

27. In. an apparatus of the character described, the combination' of alluid-containv ing vessel `that is heated by the suns drays with'ajaclmtfor. the vessel comprisin glass tubes located one within the other ansepa-' A.rated ,a space from whichthe air has been 28. In an apparatusof the character described, the combination of a {luid-containing vesselthat is heated externally by the suns rays, with a jacket'therefor comrising glass tubes, one within the other an separated by a space to forma chamber from which the air is exhausted, and means for v supportingthe inner tube HWithin the outer. 29.- In a power system, thecombination of a fluid-containing vessel that isheated externally by therays of the sun, a jacket therefor forming 'a vacuum chamber and havingatransparent portion, reflecting surfaces'for -focusing' the rays of thesun on the vessel, other reflecting surfaces for focusin the radiationfrom the vessel upon it, an conduits for conveying liquid to the vesseland vapor from it. l

30. In an apparatus of the character' described, -the combination of afluid-containing v essel that is heated by the rays of the plurality of`sol of Whichh s a vacuum `c amber and a transparent portion to enable.the said rays to act on the vessel. j

A32..In an 'apparatus' of 'the character described, the combination ofa'plurality of units that contain fluid and are adapted to be heated bythe rays of the sun, a header to f whichA the units are attached, ahinged support forthe header, conduits for conveyin lfluid to and fromthe header through sai support, and jackets for the units to reduce thedissipation ofheat therefrom, each of which has a vacuum chamber.

'In witness whereof, I .have hereunto set mydland this 29..-day of' May,1909.

, L.-n.`EmtE'r.- ".Witnesses: i' l v F. MACDONALD,

, BENJAMIN B.\HULL. t

